Two of the most effective exercises for firming your legs and butt are squats and lunges.

Squats can be done with barbell weights in your hands, a metal or padded bar across your shoulders behind your head. You can keep your feet, shoulder width apart, or wider with your toes slightly turned out. Be careful of your knee's during squats and if you feel any tweaking pain, STOP!

Standing or walking lunges are highly effective. With or without additional weights in hand, lunges generate intense contractions in one leg at a time. This isolates the glutes and hamstrings. No doubt, if you so several sets ( making sure your bending knee does not extend over the front of your foot- protect your joints) of these...you feel them in the morning!